structure and functions of pancreas are discussed.

1. PANCREAS
By Anukrity & Akanksha
Msc.Final (Zoology)
Bareilly College, Bareilly

2. CONTENTS
What is Pancreas & its secretion
Regulation of Pancreatic Secretion
& Endocrine Function
Insulin & its synthesis
Glucagon & its function
Abnormalities of Insulin

3. ◦ Pancreas is a compound elongated
organ situated between the limbs of
the ‘C’ shaped duodenum.
◦ The exocrine portion secretes an
alkaline pancreatic juice & endocrine
portion secretes hormones .
◦ It is a part of digestive gland which is
associated with alimentary canal.
◦ It is a second largest gland having
length of 12 to 15 cm & width 2.5 cm in
humans.
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What is Pancreas ?

4. “
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Cystic duct from Gall bladder joins with
the common hepatic duct & forms CBD
CBD Joins with the Pancreatic duct and
forms hepato-pancreatic duct
It opens into Duodenum which is guarded
by a sphincter of Oddi
H=Head
N=Neck
B=Body
T=Tail
Un=Uncinate

5. o Pancreatic secretion contain multiple enzymes for
digesting all of the three major types of food : Proteins,
Carbohydrate & Fats.
o The pancreatic digestive enzymes are secreted by
pancreatic acini, and large volumes of bicarbonate by duct
cell.
o Pancreas produces 200-800 ml per day which is a
colourless fluid having a pH of about 8.
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7. Trypsinogen is converted into Trypsin by
Entrokinase which is responsible for activation
of Proteolytic digestive enzymes for example
chymotrypsinogen, etc.
Trypsinogen Trypsin
Enterokinase
Chymotrypsinogen
Procarboxypeptidase
Proelastase
Prophospholipase
Chymotrypsin
Carboxypeptidase
Elastase
Phospholipase
Entrokinase, is secreted by the intestinal mucosa
when chyme comes in contact with the mucosa.

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(B) Amylolytic Enzymes: are those enzymes that degrade starch
Amylase hydrolyses starch to maltose & act optimally at a neutral to slightly alkaline
medium.
All the disaccharides splitting enzymes although found in pancreatic juice.
(A)Proteolytic enzyme: are those enzymes that breaks down the protein such as trypsin,
chymotrypsin, and carboxypolypeptidase.
o Trypsin and chymotrypsin split whole and partially digested proteins into peptide.
o However, carboxypolypeptidase splits some peptides into individual amino acids, thus
completing digestion of some proteins all the way to the amino acid state.
Trypsin & Chymotrypsin Carboxypolypeptidase
Partially Digested Protein Peptide Amino acid

9. (C) Lipotylic enzymes
o The Pancreatic juice contains a Pancreatic lipase, known as Steapsin
o It hydrolyses fats into glycerol, fatty acids & Monogylceride
o Cholesterol esterase which cause hydrolysis of cholesterol.
(D) Pancreatic nucleases
Two polynucleotides occur in the pancreatic juice, for hydrolysing RNA
and other DNA.
(E) Bicarbonate & water
When the pancreas is stimulated to secrete copious quantities of
pancreatic juice, the bicarbonate ion concentration can rise about five
times that of bicarbonate ions in the plasma which makes it alkali in
nature.
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11.  The endocrine pancreas consist of ‘Islet of
Langerhans’ .
 There are about 1 to 2 million of islet of
Langerhans in a normal human pancreas
representing 2 % of pancreatic tissue.
 The Islet contain 4 cells
 alpha cells consisting about 25% of islet,
which lies periphery & secrete glucagon
 beta cells consisting about 60% of islet,
which lies middle & secrete insulin &
amylin
 Delta cells consisting about 10% of islet
which lies in between & produces
somatostatin
 PP cells (5%) produces pancreatic
polypeptide 11
Islet of Langerhans

12. • Discovery: Insulin was first isolated from the Dog’s
pancreas in 1922 by Banting and Best.
• Synthesized by beta cells & it is composed by 2 amino
acid chain connected by disulfide linkage.
◦ Insulin is synthesized by Insulin RNA by ribosome
attached to ER & forms Preproinsulin.
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Preproinsulin it cleaves in
Endoplasmic reticulum to form
Proinsulin
Proinsulin
•Consisting A,B & C chain & it further cleaved in
Golgi apparatus to form Insulin
Insulin : it is packed in the secretory
granules

13. Activation of Target Cell Receptors by Insulin
& the resulting cellular effects
o To initiate its effects on target cells, insulin
first binds with and activates a membrane
receptor protein.
o The insulin receptor is a combination of four
subunits held together by disulfide linkages.
o The insulin binds with the alpha subunits on
the outside of the cell, due to the linkages
with the beta subunits, the portions of the
beta subunits protruding into the cell become
auto phosphorylated.
o Which in turn causes phosphorylation of
multiple other intracellular enzymes including
a group called insulin-receptor substrates (IRS).
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Effect on Carbohydrate
Metabolism
o It promotes Liver uptake
& use of glucose.
o Promotes conversion of
Glucose into fatty acids.
o Promotes in storage of
fat in the adipose cells.
o Promotes of uptake of
glucose
transporters(GLUT
2,4,3) that permit
glucose influx.
Effect On Protein
Metabolism
o It Promotes protein
synthesis and
storage
o Insulin & growth
hormone interact
synergistically to
promote growth.

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 Glucagon is a single polypeptide chain
hormone secreted by alpha cell.
 Glucagon mainly acts by maintaining blood
glucose level by increasing glycogenlysis &
gluconeogenesis in liver cell.
 It also activates adipose cells lipase making
increase quantities of fatty acid.
 It also enhances the strength of heart.
 Increases the blood flow in some tissue
especially Kidney.
 Enhances bile secretion .

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17. The abnormality in Insulin causes Diabetes Mellitus
o There are two general types of diabetes mellitus
o Type I diabetes also called as insulin-dependent
diabetes mellitus(IDDM) caused by lack of insulin
secretion.
o Type II diabetes also called non-insulin-dependent
diabetes mellitus(NIDDM) caused by reduced
sensitivity to insulin.
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o Guyton & Hall Textbook of Animal
Physiology
o HR Singh Animal Physiology &
Biochemistry
o Dr. KV Sastry Animal physiology &
biochemistry
o Wikipedia
o ncert

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